Methods for manufacturing an embosser drum for use in pre-formatting optical tape media

ABSTRACT

Various embodiments herein include utilities for generating embosser drums that are used to pre-format optical media such as optical tape with a pattern of nanostructures such as wobbled grooves. One utility includes generating a plurality of replicas from an embossing master and bonding the replicas together to form a bonded replica structure having a surface with the nanostructure pattern imprinted therein and a surface area that is approximately the same as an outer embossing surface of the embosser drum to be formed. Advantageously, a single, one-piece metallic shim can subsequently be generated, appropriately shaped and welded at a single seam to form the embosser drum outer embossing surface.

BACKGROUND

1. Field of the Invention

The present invention generally relates to devices and processes forpre-formatting optical media such as optical tape, and more particularlyto a process of producing or fabricating an embosser drum for use inperforming continuous roll-to-roll nanoimprint lithography to pre-formatoptical tape.

2. Relevant Background

Optical tape is a type of digital storage media that is generally in theform of a long and narrow strip of plastic that is designed to windaround a number of reels and be moved in first and second oppositelongitudinal directions by a drive motor (the reels and drive motorbeing known as a “tape transport system”). As the optical tape is movedabout the reels by the drive motor, digital content (e.g., binary datain the form of a series of encoding patterns) may be written and read byone or more lasers which may be embodied in one or more optical pickupunits (OPUs).

The encoded binary data may be in the form of “pits” (e.g.,indentations, indicia) and “lands” (e.g., the portion of the tapebetween adjacent pits) disposed on one or more encoding or recordinglayers (e.g., each including a dye recording layer, a phase changematerial such as AgInSbTe, and/or a semi transparent metal reflectinglayer). Pits result in decreased (e.g., distorted) reflection when readby a laser and may equate to a binary value or zero or “off” whereaslands reflect laser light and may equate to a binary value of one or“on”. Generally, the smaller the indicia are on the optical media, thehigher the capacity is of the optical media.

To enhance positioning, tracking, focusing, and the like in relation tothe optical tape and related componentry (e.g., OPUs, hardware, controlsystem, and/or the like), one or more physical features may beincorporated into one or more surfaces of the optical tape at the timeof manufacture (i.e., the optical tape may be “pre-formatted”). Forinstance, nanometer scale patterns may be imprinted in the optical tapeby way of mechanically deforming the tape (e.g., one or more monomer orpolymer layers of the tape) and curing the tape with heat or UV lightduring the imprinting. One type of nanometer scale pattern may be aseries of grooves defined on the surface of the optical tape. Encodeddata in the form of pits and the resultant lands between adjacent pitsmay be formed within grooves and/or on the portion of the opticalsurface between adjacent grooves (which may also be referred to as“lands”). The encoding may utilize any appropriate recording processsuch as helical scan recording, quadruplex recording, and/or the like.In any event, forming the encoded pattern of pits and lands withinand/or in relation to the grooves facilitates tracking of data by OPUs.In some arrangements, the pre-formatting may include forming “wobbled”grooves in the optical tape where the wobbled features on the edges ofeach groove provide addressing information in relation to the datatracks.

In relation to the pre-formatting of optical tape, “Roll-to-RollNanoimprint Lithography” has been proposed as a method to pre-formatoptical tape media with nanostructure imprints such as a series or setof generally parallel wobbled grooves. This process generally involvestransporting the optical tape through a number of operational stages byway of a tape transport system (e.g., system of reels, tensions sensors,and the like). Among others, operational stages typically includecoating and sputtering, embossing and curing. In relation to theembossing stage, the optical tape is typically wound around what may bereferred to as an “embossing” or “embosser” drum (e.g., roller) thatincludes a pattern of nanostructures which serves to emboss the patterninto the surface of the optical tape.

SUMMARY

The ability of embosser drums to accurately pre-format optical tape(e.g., by way of embossing a pattern of wobbled grooves into the surfaceof the optical tape) depends upon a number of factors. As discussedabove, an embosser drum includes a series of nanostructures that aredesigned to emboss a desired shape into the optical tape (where theshapes of the nanostructures are of an opposite shape from that of theembossed pattern in the optical tape). In this regard, the fidelity androbustness of the nanostructures formed in the surface of the embosserdrum should be maintained to achieve an accurate series of nanometerscale patterns in the surface of the optical tape.

Furthermore, an increase in the number of metallic segments or shimsused to form the nanostructured surface of the embosser drum results ina corresponding reduction in the quality and performance of the embosserdrum (i.e., reduces the ability of the embosser drum to accuratelyreproduce the nanometer scale patterns on the surface of the opticaltape). More specifically, existing embosser drum development andmanufacturing generally consists of designing the layout of thenanostructures to be formed on the outer surface of the embosser drum,producing a quartz or silicon embossing “master” that is etched with thenanostructure layout, creating a plurality of rigid polymeric replicasof the master's patterns, performing a metal plating process (e.g.,electroforming) on the surface patterns of each of the replicas togenerate thin metal “stamper” plates or shims including thenanostructure patterns, shaping each of the shims to form a plurality ofcylinder segments, welding the segments together to form a cylindricalembossing surface of an embosser drum, and then inserting a solidcylindrical core (e.g., made of rubber) into the inside of thecylindrical embossing surface to form the embosser drum.

The master is typically designed to have a width that is the same as thewidth of the final embosser drum embossing surface and a length that isa particular fraction of the circumferential length of the finalembosser drum embossing surface such that the plurality of metallicsegments formed from the replicas can be welded together at their endsto form the embosser drum embossing surface. For instance, as existingembosser drums typically include four metallic segments that are weldedtogether along a number of axial seams (i.e., seams that are generallyperpendicular to the a longitudinal dimension of the grooves of thenanostructure pattern and generally parallel to a longitudinal orrotational axis of the embosser drum) to form the outer surface of theembosser drum, the master typically has a length that is one-quarter ofthe circumferential length of the final embosser drum embossing surface.

In one regard, an increase in the number of seams (regardless of seamtype) between metallic segments equates to an increase in the number ofwelding steps that must be performed to weld the segments together.Correspondingly, an increase in the degree to which the final product ofthe embosser drum is at the mercy of each of the welding processesresults (i.e., there is an increase in the likelihood of welding errorsby a factor that is directly related to the number of segments beingused). More specifically, each welding step often results in uneven seamheight profiles (e.g., the top of a land or groove of the nanostructurepattern of one segment is not level with the top of a corresponding landor groove of the nanostructure pattern of an adjacent segment at theseam or weld junction), uneven footprints (e.g., the edge of a land orgroove of the nanostructure pattern of one segment is not aligned withthe edge of a corresponding land or groove of the nanostructure patternof an adjacent segment at the seam or weld junction), and increased seamwidths (i.e., the distance between opposing ends of adjacent cylindersegments), all of which reduce drive performance and the ability of theembosser drum to accurately form the patterns on the optical tape.Additionally, each of the various metallic segments typically must beshaped and/or formed to the shape of the surface of the embosser drum(e.g., into a portion of a cylinder) to be formed. As with the weldingprocesses, having to shape and form each segment results in an increasein the degree to which the final product of embosser drum is at themercy of the ability of the manufacturing process to accurate shape eachof the plurality of segments by a factor directly related to theparticular number of metallic segments to be used to form the embosserdrum surface.

Furthermore, the use of the axial seams (e.g., as opposed tolongitudinal seams) between the plurality of metallic segments presentselements of uncertainty and quality degradation into the nanometer scalepatterns on the surface of the optical tape. More specifically, axialseams necessarily result in transverse weld marks being imprinted acrossthe width of the optical tape at regular intervals equal to the lengthof each metallic segment. As the OPUs are required to traverse the weldmarks at each interval, the OPUs are thus subject to the flaws of suchseams each time the seams pass the OPUs. Moreover, welding seams in anaxial manner can increase the difficulty in ensuring even heightprofiles and footprints.

It has been determined by the inventors that apparatuses, methods ofmanufacture or fabrication, and the like (i.e., utilities) in relationto embosser drums are needed that are operable to reduce or limit theaforementioned inefficiencies of existing embosser drum designs andmanufacturing methods for such existing embosser drum designs. Methodsof manufacture and embosser drums produced from such manufacturingmethods will be disclosed including the use of at least one of a) an“embossing master” having an increased length and/or reduced widthcompared to previous embossing masters, b) the generation of a pluralityof first generation polymer replicas which are bonded together using atleast one longitudinal seam (i.e., as opposed to an axial seam) togenerate a bonded first replica structure having a major surface with adesired nanostructure pattern and a surface area the same as that of anouter surface of the embosser drum to be formed, c) reduced heightprofiles, footprints and widths for seams of the bonded first replicastructure as compared to seams of previous embosser drums, and d) areduced number of metallic cylinder segments (e.g., such as the use of asingle metallic cylinder) to form the embosser drum. The manufacturingmethods disclosed herein may incorporate a metal plating process thatcan accommodate the use of large polymeric replicas, a drum formingtechnique to produce an accurate drum structure from a single flatmetallic segment (e.g., stamper plate or shim) produced from the metalplating process instead of a plurality of segments (e.g., four segmentsas in existing embosser drum designs), and/or welding techniques toproduce narrower welding seams with smoother weld surfaces and reducedseam height profiles on the embosser drum.

Generally, the manufacturing methods and processes disclosed herein mayinclude the design and development of a new “embossing master” that isof an increased length as compared to those used in existing embosserdrum manufacturing processes. For instance, the master may have a lengthequal to one-half of the circumferential length of the embosser drumembossing surface which may reduce the number of axial welding seamsneeded to form the final embossing surface. The master may also bedesigned to have a width less than that used in existing master designs(e.g., half the width of existing masters).

A number of “first generation” replicas (e.g., polymeric replicas) canbe made from the embossing master and appropriately bonded together tocreate a flattened-out surface image of the embosser drum's embossingsurface (a “bonded first replica structure”). For instance, in the eventthat a master is made having a length and width that are respectivelytwice and half that of existing masters, two of four first generationreplicas can be bonded (e.g., welded) along their lengths, the other twoof the four first generation replicas can be bonded along their lengths,and then the two pairs of replicas can be bonded along their widths. Atthis point, the bonded first generation replicas now form a bonded firstreplica structure (e.g., the flattened-out shape of the outer embossingsurface of the embosser drum to be created). Alternatively, the fourfirst generation replicas can be simultaneously bonded together to formthe bonded first replica structure or bonded together in other manners.

The bonded first replica structure can then be used to create a single“second generation” polymeric replica which can then be metallized(e.g., electroformed) to generate a single thin metal stamper plate orshim (e.g., an “embossing plate”) including the nanostructure patterns.The single metal stamper plate can then be rolled into a cylindricalformation and its ends welded together to form an embosser drum having asingle seam with a reduced width and height profile as compared to theeach of the four or more axial seams of previous embosser drum designs.As some embodiments envision that a plurality of second generationpolymer replicas can be generated from the same bonded first replicastructure (each of which can be used to create a single, one-piecemetallic shim that can be shaped to form the entire outer surface of anembosser drum), the bonded first replica structure may in someembodiments essentially become a second or subsequent embossing master.In any case, any appropriate core may be inserted into the hollow centerof the cylindrically-formed single metal stamper plate. For instance, asolid (e.g., cylindrical) rubber core may be compressed, inserted intothe hollow center of the cylindrically-formed stamper plate, and allowedto expand to form a sturdy embosser drum.

Creation of the bonded first generation structure advantageouslyessentially replaces one or more of the axial seams of existing embosserdrum manufacturing processes with circumferential seams that, once theembosser drum is ultimately formed, will have less negative impact onthe pre-formatting process (e.g., on drive performance), the ability ofan OPU to accurately read data of pre-formatted optical tape, and thelike. Furthermore, the bonding of “first generation” polymeric replicas(to form a bonded first generation replica having a length and width thesame or substantially the same as that of the final embosser drum outersurface) allows for seam width and height profiles that are reduced ascompared to those results from the welding of the metal cylindersegments of previous embosser drum manufacturing methods. That is,reduced seam width and height profiles can be achieved when bonding flatpolymeric segments together as compared to welding cylindrically-shapedmetal segments together as in previous manufacturing methods. In anycase, the disclosed manufacturing methods generate embosser drums thatcan more accurately pre-format optical tape due to the use of a reducednumber of cylinder segments (e.g., the single thin metal stamper plateformed from the single second generation polymeric replica), one or morecircumferential welded seams (i.e., as opposed to axial seams), reducedwidth and height profiles for seams, and/or a lower overall number ofwelding seams.

Any of the embodiments, arrangements, or the like discussed herein maybe used (either alone or in combination with other embodiments,arrangement, or the like) with any of the disclosed aspects. Merelyintroducing a feature in accordance with commonly accepted antecedentbasis practice does not limit the corresponding feature to the singularAny failure to use phrases such as “at least one” does not limit thecorresponding feature to the singular. Use of the phrase “at leastgenerally,” “at least partially,” “substantially” or the like inrelation to a particular feature encompasses the correspondingcharacteristic and insubstantial variations thereof. Furthermore, areference of a feature in conjunction with the phrase “in oneembodiment” does not limit the use of the feature to a singleembodiment.

In addition to the exemplary aspects and embodiments described above,further aspects and embodiments will become apparent by reference to thedrawings and by study of the following descriptions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a Roll-to-Roll Nanoimprint Lithographyprocess.

FIG. 2 is a schematic diagram of a process for manufacturing an embosserdrum for use with the Roll-to-Roll Nanoimprint Lithography process ofFIG. 1, according to the prior art.

FIG. 3 is a schematic diagram of a process for manufacturing an embosserdrum for use with the Roll-to-Roll Nanoimprint Lithography process ofFIG. 1, according to one embodiment.

FIG. 4 is a flow diagram for use in manufacturing the embosser drumillustrated in FIG. 3.

DETAILED DESCRIPTION

Various embodiments herein include utilities directed to themanufacturing of embosser drums for use in pre-formatting optical mediasuch as optical tape. The disclosed utilities generate embosser drumsthat are able to more accurately form or imprint a series ofnano-structures (e.g., wobbled grooves) into the surface of the opticalmedia due to a reduced number of seams (e.g., a single seam) compared toprevious embosser drums, a reduced width and height profile of thesingle seam compared to those of each of the plurality of seams ofprevious embosser drums, and the like. As will be discussed, the reducednumber of seams and seam width and height profiles result from the useof one or more circumferential seams (as opposed to axial seams) in oneor more intermediate stages of the disclosed utilities in addition tobonding polymeric segments together into a first bonded replicastructure during one or more intermediate steps (instead of weldingmetal cylinder segments together as part of a final step of an embosserdrum manufacturing process).

Turning now to FIG. 1, a schematic diagram of a system 100 isillustrated for use in pre-formatting optical media such as a length ofoptical tape 104 (e.g., to form a series or pattern of grooves into atleast one of the first and second opposing surfaces of the optical tape104). In one arrangement, the system 100 may implement a “Roll-to-RollNanoimprint Lithography” process including a number of operationalstages or stations (each including any appropriate tool(s) and/ormachinery) that systematically pre-format the optical tape 104 withnanometer-scale imprints such as a series or pattern of wobbled grooves(e.g., where each groove generally facilitates data tracking and thewobbled features of each groove generally facilitate data trackaddressing). As just one example for the purposes of context, eachwobbled groove may have a depth of about 20 nanometers and a width ofabout 360 nanometers. OPUs can detect the various wobbled features assine waves which can be decoded to obtain addressing information. In anyevent, while a number of operational stations will now be described, itshould be understood that such stations may occur in an order differentthan that shown in FIG. 1 as appropriate, and also that additional ordifferent stations may be utilized in the system 100 without departingfrom the scope of the present disclosure.

The system 100 may include any appropriate tape transport system 108that is generally operable to move the optical tape 104 in first and/orsecond opposite longitudinal directions through the various operationalstations. The tape transport system 108 may include at least one supplyreel 112 for supplying optical tape 104 that needs to be pre-formatted(e.g., in the form of a polyester substrate or basefilm), at least onetake-up reel 116 for receiving optical tape 104 that has beenpreformatted in the system 100, a number of rollers 120 for guiding theoptical tape 104 through the various operational stations, and one ormore drive motors (not shown) for inducing movement of the optical tape104 in the first and/or second opposite longitudinal directions.Furthermore, and although not shown, the system 100 may include or beassociated with any appropriate computing system including a processingunit (e.g., CPU), memory unit (e.g., RAM), and one or more programsincluding protocols or logic storable in the memory unit and executableby the processing unit for controlling operation of the system 100. Thecomputing system may also include any appropriate I/O devices (e.g.,keyboard, mouse, display, and the like).

One station of the system 100 may be an embossing monomer coatingstation 124 that is operable to coat a substrate or basefilm of theoptical tape 104 with a layer of any appropriate liquid monomer intowhich a pattern of nanostructures may subsequently be formed. Once theoptical tape 104 has left the embossing monomer coating station 124, theoptical tape 104 may enter an embossing/curing station 128 that isgenerally operable to emboss nanostructure patterns into the liquidmonomer layer and cure the liquid monomer layer to convert the liquidmonomer layer into a solid polymer layer (e.g., an “embossed layer”). Asshown, the embossing/curing station 128 includes an embosser drum 132that rotates about an axis 133 and that has a nanostructure pattern onits outside surface (not shown in FIG. 1) for imprinting a nanostructurepattern of grooves into the liquid monomer layer. For instance, one ofthe rollers 120 may be a nip roller 130 that is operable to press theoptical tape 104 against the nanostructure pattern on the outer surfaceof the embosser drum 132 to cause the imprint of the nanostructurepattern in the liquid monomer layer. Furthermore, the embossing/curingstation 128 also includes a curing device 136 that emits UV light (orother type of light or heat) towards the optical tape 104 to cure theoptical tape 104 and thus set the nanostructure pattern into theembossed layer of the optical tape 104.

The system 100 may include one or more additional chemicalcoating/sputtering stations 140 for use in creating or forming on theoptical tape 104 a reflective layer (e.g., to reduce noise in reflectedlaser light read by OPUs), a phase change film, an overcoat, a topcoat,and/or the like as appropriate. Furthermore, the system 100 may includea tension sensor/controller station 144 for use in maintainingappropriate tension in the optical tape 104 as the optical tape 104moves through the system 100 and a tape slitting station 148 for use inlongitudinally slitting or cutting the optical tape 104 into a pluralityof narrower sections of optical tape 104. As mentioned above, more,fewer or different stations may be included in the system 100 withoutdeparting from the scope of the present disclosure. For instance, whilethe embossing and curing of the optical tape 104 have been shown as partof a common station, other embodiments envision that such steps could bepart of separate stations.

Turning now to FIG. 2, a schematic flow diagram of a process 200 ofmanufacturing an embosser drum according to the prior art and usable inthe embossing/curing station 128 of the system 100 of FIG. 1 isillustrated. Although not shown, the process 200 utilizes anyappropriate tools, machines and the like to obtain the variouscomponents shown throughout the process 200. Furthermore, anyappropriate computing system (with processor, memory, logic, and thelike) may be in communication with the various tools and machines todrive construction of the embosser drum. The process 200 begins with theretrieval of one or more format or layout files 204 including thespecific nanostructure pattern design to be formed on the outsidesurface of the embosser drum (for use in imprinting an oppositenanostructure pattern into the liquid monomer layer of the optical tape104 of FIG. 1). The particular nanostructure pattern 210 is then formed(e.g., etched) on at least one surface of an embossing master 208 thatis constructed of any appropriate material (e.g., quartz, silicon) andof any appropriate dimensions (e.g., approximately 5″×5″×½″). Theembossing master 208 is typically constructed to have a width 212 thatis approximately the same as an axial width 218 of the embosser drum 216to be formed (e.g., 5 inches) and a length 214 that is approximatelyone-quarter of a circumference 220 of the as yet formed embosser drum216 (e.g., 5 inches). In some arrangements, the width 212 and length 214of the embossing master 208 may in actuality be slightly larger than theaxial width 218 and one-quarter of the circumference 220 of the as yetformed embosser drum 216, respectively (e.g., on the order of fractionsof an inch or even millimeters larger). In this regard, the outersurface of the embosser drum (e.g., four metallic shims 228, discussedmore fully below) is more precisely cut or otherwise formed at a laterstep of the process 200.

From the embossing master 208, a number of polymer replicas 224 (e.g.,rigid plastic replicas, only one of which has been labeled for clarity)are formed, where the number is selected as a function of the fractionof the circumference 220 represented by the length 214 of the embossingmaster 208. Stated differently, a particular number of polymer replicas224 are made such that if such polymer replicas 224 were attachedlengthwise in an end to end manner and subsequently wrapped around theouter surface of the yet to be formed embosser drum 216, the outersurface of the embosser drum 216 would be substantially fully covered.In this case, as the length 214 of the embossing master 208 isone-quarter of the circumference 220 of the yet to be formed embosserdrum 216, four polymer replicas 224 are made. As the name implies, eachpolymer replica 224 is an exact or substantially exact replica (e.g., interms of dimensions, surface features such as the nanostructure pattern210, and the like) of the embossing master 208. In the interest ofclarity, reference numeral 210 will be used to refer to thenanostructure pattern on all of the various components of the process200.

After generation of the polymer replicas 224, a metallic stamper plateor shim 228 is formed from each of the polymer replicas 224 (e.g., viaany metallizing process such as eletroforming or electroplating), whereeach shim 228 includes the same length and width dimensions of itsrespective polymer replica 224 in addition to the nanostructure pattern210 (all of which are the same as those of the embossing master 208).Each of the four shims 228 is then typically precisely cut (so that thefour shims 228 when arranged in an end-to-end manner have a surface areasubstantially equal to those of the as yet formed embosser drum outersurface) and appropriately shaped (e.g., via one or more rollers) toform a cylindrical or cylinder segment 232 which will form a portion ofthe outer surface 236 of the embosser drum 216 to be formed. Thecylinder segments 232 are then arranged end-to-end and welded togetherat four different seams 240 (only one of which has been labeled forclarity) to form the embosser drum 216. Each of the seams are typicallyin the range of 0.6 mm-0.8 mm such as about 0.7 mm.

As shown, the outer surface 236 of the embosser drum 216 includes thenanostructure pattern 210 whereby the individual structures (e.g., thegrooves) of the nanostructure pattern 210 generally extend in acircumferential direction around the embosser drum 216. In this regard,and when used in the system 100 of FIG. 1, the embosser drum 216 mayemboss or imprint the nanostructure pattern 210 into the liquid monomerlayer of the optical tape 104 such that individual structures of thenanostructure pattern 210 extend along a length of the optical tape 104.For stability and while not shown, a compressible core (e.g.,cylindrical portion of rubber) is typically compressed, inserted into ahollow interior 244 of the embosser drum and allowed to expand againstinside surfaces of the cylinder segments 232 to form a substantiallysolid structure.

As discussed previously, the embosser drum 216 of the prior art suffersfrom a number of design flaws that lead to the inefficient andinaccurate pre-formatting of optical tape (e.g., the use of multiplemetallic segments welded together at multiple axial seams to form theembosser drum's outer surface leading to misalignment of correspondinggrooves or lands of adjacent segments, the use of multiple welding stepsto connect adjacent segments resulting in an increased degree to whichthe final product of the embosser drum is at the mercy of each of themultiple welding steps, and the like). With reference now to FIG. 3, aschematic diagram of a process 300 is shown for manufacturing anembosser drum (e.g., usable with the system 100 of FIG. 1) that reducesthe problems and inefficiencies associated with previous embosser drumdesigns and manufacturing methods (such as those associated with FIG.2). Any appropriate computing system (with processor, memory, logic, andthe like) may be in communication with one or more various tools andmachines to drive construction of the embosser drum of FIG. 3. Theprocess 300 of FIG. 3 will be discussed in conjunction with the method400 illustrated in FIG. 4.

As shown in FIG. 4, the method 400 may include obtaining 404 anembossing master including a pattern of nanostructures on at least onemajor surface of the embossing master. In one arrangement, the obtaining404 may include, as shown in FIG. 3, retrieving of one or more format orlayout files 304 including the specific nanostructure pattern 310 (e.g.,including a series or set of grooves 311) to be formed on the outsidesurface 336 (e.g., outer embossing surface) of the embosser drum 316 tobe formed (which may be the same as the nanostructure pattern 210 ofFIG. 2). For instance, an operator may appropriately select and load alayout file 304 into an associated computing system corresponding to adesired wobbled groove pattern to be formed on the embosser drum, andthe computing system may coordinate with the various machines and toolsto construct an embosser drum having a corresponding wobbled groovepattern. Thereafter, the nanostructure pattern 310 may be etched into atleast one of opposing major surfaces 315 of an embossing master 308formed of any appropriate material (e.g., silicon).

Unlike previous embossing masters (e.g., the embossing master 208 ofFIG. 2), the embossing master 308 of FIG. 3 may be constructed orotherwise selected to have a width 312 that is less than an axial width318 of the embosser drum 316 to be formed and/or a length 314 that is agreater fraction of a circumference 320 of the yet to be formed embosserdrum 316 than are previous embossing master lengths for reasons thatwill become more apparent in the ensuing discussion. For instance, thewidth 312 of the embossing master 310 may be half of the axial width 318of the as yet formed embosser drum 316 and the length 314 of theembossing master 310 may be half of the circumference 320 of the as yetformed embosser drum 316, resulting in the embossing master 308 havingdimensions of approximately 2½″×10″×½″). Other dimensions of theembossing master 308 are also contemplated and encompassed within thescope of the present disclosure. In some arrangements, the width 312 andlength 314 of the embossing master 308 may in actuality be slightlylarger than half the axial width 318 and half the circumference 320 ofthe as yet formed embosser drum 316, respectively (e.g., on the order offractions of an inch or even millimeters larger). In this regard, theouter surface of the embosser drum (e.g., a single metallic shim 364,discussed more fully below) is more precisely cut or otherwise formed ata later step of the process 300 and/or method 400.

In any case, the method 400 may include making 408 a plurality of firstgeneration polymer replicas 324 from the embossing master 308. As thename implies, each first generation polymer replica may be an exact orsubstantially exact replica (e.g., in terms of dimensions, surfacefeatures such as the nanostructure pattern 310, and the like) of theembossing master 308. As shown, each polymer replica 324 may include apair of generally opposing end surfaces 328, a pair of generallyopposing side surfaces 332, and a pair of generally opposing top andbottom or “major” surfaces 337. At least a first of the major surfaces337 of each of the polymer replicas 324 includes the nanostructurepattern 310. The particular number of polymer replicas 324 may be suchthat, when the surface areas of the first major surfaces 337 includingthe nanostructure patterns 310 of such particular number of replicas 324are summed, a value substantially equal to (e.g. , slightly larger than)a surface area of an outer surface 336 of the yet to be formed embosserdrum 316 results. In the illustration of FIG. 3, four first generationpolymer replicas 324 may be generated and used to eventually form theembosser drum 316.

Once the first generation polymer replicas 324 have been generated, thefirst generation polymer replicas 324 may be bonded together to create412 a bonded first replica structure 340 having opposing major surfaces352. Each opposing major surface 352 has a surface that is at leastsubstantially the same as (e.g., slightly larger than) that of the outersurface 336 of the yet to be formed embosser drum 316. Furthermore, thefirst generation polymer replicas 324 are bonded together to form thebonded first replica structure 340 in a manner that utilizes at leastone longitudinal seam (i.e., a seam that runs generally parallel to thelongitudinal direction of the grooves 311 of the nanostructure pattern310). Advantageously, a structure is formed (i.e., the bonded firstreplica structure 340) having a first major surface 352 with thenanostructure pattern 310 formed therein and having a reduced number orlength of axial seams (i.e., seams that run generally perpendicular to alongitudinal direction of the grooves 311 of the nanostructure pattern310) compared to previous embosser drums. For instance, the number orlength of axial seams of the bonded first replica structure 340 is lessthan that of the embosser drum 216 (which, as seen in FIG. 2, includesfour axial seams, or three axial seams if flattened out, but nolongitudinal/circumferential seams).

As will be discussed later on this discussion, the bonded first replicastructure 340 can be used to form at least one single “secondgeneration” polymer replica 356 that is at least substantially or fullydevoid of any seams and which can be used to produce a single metallicshim 364. Each single metallic shim 364 can be appropriately shaped andwelded along a single axial seam 384 (as opposed to the plurality ofaxial seams 240 of the prior art embosser drum 216) to form a respectiveembosser drum 316. Reducing the number of axial seams used in themanufacturing processing of an embosser drum as shown in the process 300of FIG. 3 advantageously reduces at least some of the inefficiencies andother problems associated with the prior art embosser drum 216 and itsassociated manufacturing method (e.g., by limiting the degree to whichan OPU must traverse axial seams while reading a portion of opticaltape). Furthermore, bonding the first generation replicas 324 togetherinstead of welding such replicas 324 together (as are the four cylindersegments 232 of the prior art embosser drum 216) advantageously allowsfor a more accurate and precise alignment and connection of adjacentfirst generation polymer replicas 324 as well as reduced seam widths(e.g., on the order of 0.20 mm-0.30 mm) (e.g., due to the fact thatwelding results in melted metal solidifying within the seams, amongother reasons).

For instance, opposing side surfaces 332 of first and second polymerreplicas 324 (e.g., forming a first pair 338) may be bonded together ata longitudinal seam 342, opposing side surfaces of third and fourthpolymer replicas 324 (e.g., forming a second pair 339) may be bondedtogether at a longitudinal seam 343 that is generally collinear with thelongitudinal seam 342, and then opposing end surfaces 328 of the firstand second pairs 338, 339 may be bonded together such that the bondedfirst replica structure 340 includes a longitudinal seam 344(collectively including the longitudinal seams 342, 343) and an axialseam 348 that is at least substantially perpendicular to thelongitudinal seam 344. In one arrangement, the first generation polymerreplicas 324 may be bonded together as discussed above at leastsubstantially simultaneously. For instance, the first generation polymerreplicas 324 may be arranged on a surface (e.g., a glass surface) withthe “active” surfaces (e.g., those including the nanostructure patterns310) facing away from the surface and then bonded together as discussedabove. In another arrangement, the first pair 338 may be bonded togetherand the second pair 339 may be bonded together, and then the first andsecond pairs 338, 339 may be bonded together along their end surfaces328 at axial seam 348 (which includes respective axial seams betweenadjacent polymer replicas 324). In further arrangements, the bondedfirst replica structure 340 may include only first and second polymerreplicas 324 bonded at their respective side surfaces along alongitudinal seam (each having a length the same as the circumference320 of the embosser drum 316 to be formed) or more than four polymerreplicas 324. In any case, the bonded first replica structure 340 mayinclude opposing major surfaces 352, at least a first of which includesthe nanostructure pattern 310 formed therein.

From the first bonded replica structure 340, a single “secondgeneration” polymer replica 356 may be produced 416 including opposingmajor surfaces 360, at least a first of which includes the nanostructurepattern 310 formed therein. As shown, the second generation polymerreplica 356 may be devoid of any seams and may thus constitute a single,integral, one-piece structure where a surface area of each of theopposing major surfaces 360 is at least substantially the same as (e.g.,slightly larger than) that of the outer surface 336 of the yet to beformed embosser drum. From the single second generation polymer replica356, a single metallic (e.g., nickel) stamper plate or shim 364 may begenerated 420 (e.g., via any metallizing process such as eletroformingor electroplating). Like the bonded first replica structure 340 and thesecond generation bonded replica 356, the metallic shim 364 includesopposing major surfaces 368, at least one of which includes thenanostructure pattern 310 therein.

The single metallic shim 364 may then be appropriately shaped 424 (e.g.,via one or more rollers) to form a single “substantial” cylinder 372which will form the entire outer surface 336 of the embosser drum 316 tobe formed. In some arrangements, the single metallic shim 364 may firstbe cut (e.g., laser cut) to the precise or substantially precisedimensions of the as yet formed embosser drum 316 before being shapedinto the substantial cylinder 372. In any event, first and second endsurfaces 376, 380 of the single cylinder segment 372 may beappropriately welded 428 along a single seam 384 (e.g., by aligningcorresponding grooves adjacent the first and second end surfaces 376,380 in both radial and lateral directions, limiting a width of thesingle seam 384, reducing weld spatter, and the like) to form theembosser drum 316. For stability and while not shown, a compressiblecore (e.g., cylindrical portion of rubber) may be compressed, insertedinto a hollow interior 388 of the embosser drum and allowed to expandagainst a second major surface 368 of the cylinder 372 (opposite thefirst major surface 368 including the nanostructure pattern 310) to forma substantially solid structure. It is noted that the single cylinder372 has been referred to as a single “substantial” cylinder 372 toconnote that the first and second end surfaces 376, 380 have not yetbeen welded together. Furthermore, it should be understood that thesingle substantial cylinder 372 is the same physical piece of materialas the single metallic shim 364. Thus, the opposing major surfaces 368,first and second end surfaces 376, 380 and the like are common betweenthe single metallic shim 364 and the single substantial cylinder 372.

The process 300 and method 400 of FIGS. 3 and 4 for manufacturing theembosser drum 316 present numerous advantages over previous embosserdrum manufacturing processes and methods (e.g., such as that of FIG. 2).As discussed previously, the dimensions of the embossing master 308(e.g., the length 314 and width 312) are selected so that the firstgeneration polymer replicas 324 can be bonded together in a manner thatutilizes at least one or more longitudinal seams between adjacent firstgeneration polymer replicas 324 (i.e., seams that are generally parallelto a longitudinal direction of grooves 311 of the nanostructure pattern310 of the first generation polymer replicas 324) to form a firstpolymer replica structure 340 having a first major surface 352 includingthe nanostructure pattern 310 and a surface area substantially the sameas that of the outer surface 336 of the yet to be formed embosser drum316. Advantageously, a structure is formed (i.e., the bonded firstreplica structure 340) having a first major surface 352 with thenanostructure pattern 310 formed therein and having a reduced number orlength of axial seams and a corresponding reduction in theinefficiencies that are associated with axial seams as compared to priorart embosser drums and manufacturing methods therefore. Additionally,any longitudinal bonding marks in the bonded first replica structure 340that are passed on to the second generation polymer replica 356 andultimately to the outer surface 336 of the embosser drum 316 will haveless impact on OPUs and subsequent signal processing because the OPUsneed not necessarily traverse longitudinally oriented marks as they dowith axially oriented marks.

Furthermore, bonding the first generation replicas 324 together insteadof welding such replicas 324 together (as are the four cylinder segments232 of the prior art embosser drum 216) advantageously allows for a moreaccurate and precise alignment and connection of adjacent firstgeneration polymer replicas 324 as well as reduced seam widths (e.g., onthe order of 0.20 mm-0.30 mm). Still further, in embodiments where aplurality of second generation replicas are formed from the same bondedfirst replica structure 340 (each being devoid of seams and each havingat least one major surface 360 with the nanostructure pattern 310therein and a surface area substantially the same as that of the outersurface 336 of the embosser drum 316 to be formed), the bonded firstreplica structure 340 can essentially become a second or subsequent“embossing master”. Each single second generation replica 356 canmetalized to form a single metallic shim 364 which can be cut and/orshaped into a substantial cylinder 372 and welded at a single axial seam384 along first and second end surfaces 376, 380 to form an embosserdrum 316 having a single axial seam 384 as opposed to the plurality ofaxial seams 240 of the prior art embosser drum 216.

While this specification contains many specifics, these should not beconstrued as limitations on the scope of the disclosure or of what maybe claimed, but rather as descriptions of features specific toparticular embodiments of the disclosure. Furthermore, numerous otherarrangements are envisioned. For instance, while the embossing master308 and thus each of the first generation polymer replicas 324 have beenillustrated as being generally rectangular (e.g., having generallyopposing and parallel side and end surfaces 332, 328), the presentdisclosure is not so limited. In some arrangements, an embossing master308 may be generated having non-parallel end surfaces. For instance, oneof the end surfaces may form a first non-normal angle (e.g.,) 45° with afirst of the side surfaces and a second non-normal angle (e.g.,) 135°with a second of the side surfaces. In this regard, the embossing master308 and thus each of the first generation polymer replicas 324 mayresemble a trapezoid. For instance, the end surfaces 328 of adjacentfirst generation polymer replicas 324 may be asymmetricallyinterconnected to create a bonding seam that forms a non-normal anglewith the longitudinal seam 344 (e.g., 45° or 135′). This arrangement mayfurther reduce the use of perfectly axial bonding seams (i.e., thosethat extend at least substantially perpendicularly to the grooves of thenanostructure pattern 310) and the associated inefficiencies. In anotherarrangement, the embossing master 308 and first generation polymerreplicas 324 may be appropriate shaped to result in the single bondingseam 384 of the embossing drum 316 being other than substantiallyperpendicular to the grooves of the nanostructure pattern 310.

In another embodiment, the teachings herein may be utilized to createmore than a single embossing plate/metallic shim (but fewer than thefour or more used in previous embosser drum designs) which may beappropriately welded or bonded together to form an embosser drum stillhaving a reduced number and/or length of axial seams. For example,embossing master replicas may be bonded together to create a bondedfirst replica structure having opposing major surfaces, each of whichhas a surface area equal to half that of the embosser drum to be formed.In this regard, two second generation replicas may be formed from thebonded first replica structure and then welded together at two seams toform the embosser drum. Other manners of forming embosser drums withfewer seams than previous embosser drums are also envisioned.

Furthermore, certain features that are described in this specificationin the context of separate embodiments can also be implemented incombination in a single embodiment. Conversely, various features thatare described in the context of a single embodiment can also beimplemented in multiple embodiments separately or in any suitablesubcombination. Moreover, although features may be described above asacting in certain combinations and even initially claimed as such, oneor more features from a claimed combination can in some cases be excisedfrom the combination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. In certain circumstances, multitasking and/or parallelprocessing may be advantageous. Moreover, the separation of varioussystem components in the embodiments described above should not beunderstood as requiring such separation in all embodiments, and itshould be understood that the described program components and systemscan generally be integrated together in a single software and/orhardware product or packaged into multiple software and/or hardwareproducts.

The above described embodiments including the preferred embodiment andthe best mode of the invention known to the inventor at the time offiling are given by illustrative examples only.

1. A method for use in fabricating an embosser drum, comprising: makinga plurality of replicas of an embossing master, wherein each of thereplicas includes a pattern of nanostructures; bonding the plurality ofreplicas of the embossing master together in a particular orientation tocreate a bonded replica structure including a surface having a patternof nanostructures thereon, wherein the pattern of nanostructures on thesurface of the bonded replica structure comprises the combination of thepatterns of nanostructures of the plurality of replicas; producing areplica of the bonded replica structure; and generating an embossingplate from the replica of the bonded replica structure.
 2. The method ofclaim 1, wherein the embossing plate includes a pair of opposing endsurfaces and a pair of opposing major surfaces, wherein the embossingplate includes the pattern of nanostructures on a first of the opposingmajor surfaces, and wherein the method further comprising: welding theopposing end surfaces of the embossing plate together at a single seamto form an embosser drum, wherein an outer embossing surface of theembosser drum comprises the first major opposing surface of theembossing plate.
 3. The method of claim 1, wherein each embossing masterreplica includes a pair of opposing end surfaces and a pair of opposingside surfaces, wherein a length of the side surfaces is greater than alength of the end surfaces, and wherein the bonding comprises: bondingfirst and second embossing master replicas together along respectiveside surfaces at a first bonding seam.
 4. The method of claim 3, whereineach embossing master replica comprises a pair of opposing majorsurfaces, wherein a first of the major surfaces includes the pattern ofnanostructures, wherein the pattern of nanostructures comprises a set ofgenerally parallel grooves, and wherein the first bonding seam extendsgenerally parallel to the set of generally parallel grooves.
 5. Themethod of claim 4, wherein the bonded first replica structure comprisesa pair of opposing major surfaces, wherein a first of the major surfacesincludes the pattern of nanostructures, and wherein the first of themajor surfaces comprises a surface area that is at least substantiallythe same as the outer embossing surface of the embosser drum.
 6. Themethod of claim 3, wherein the bonding further comprises: bonding thirdand fourth embossing master replicas together along respective sidesurfaces at a second bonding seam; and bonding the first and secondembossing master replicas to the third and fourth embossing masterreplicas along respective end surfaces at a third bonding seam, whereinthe first and second bonding seams are at least substantially collinear,and wherein the first and second bonding seams are at leastsubstantially perpendicular to the third bonding seam.
 7. The method ofclaim 6, wherein the bonding steps occur at least substantiallysimultaneously.
 8. The method of claim 1, wherein the outer embossingsurface of the embosser drum has an axial width and a circumference, andwherein a width of the embossing master is approximately half the axialwidth of the embosser drum, and wherein a length of the embossing masteris approximately half of the circumference of the embosser drum.
 9. Anembosser drum for use in pre-formatting optical tape media, wherein theembosser drum is fabricated using the method of claim
 1. 10. A methodfor producing at least one embosser drum that has a pattern ofnanometer-scale grooves formed in an outer surface thereof, the methodcomprising: producing a plurality of replicas of an embossing masterthat has at least one surface with the pattern of nanometer-scalegrooves therein, wherein each of the replicas comprises at least onesurface with the pattern of nanometer-scale grooves therein; bonding theplurality of replicas together to create a bonded replica structurehaving at least one surface with the pattern of nanometer-scale groovesformed therein, wherein the bonded replica structure comprises at leastone bonding seam between adjacent embossing master replicas that extendsgenerally parallel to the nanometer-scale grooves, and wherein a surfacearea of the at least one surface of the bonded replica structure is atleast substantially the same as a surface area of the outer surface ofthe embosser drum to be formed; and using the bonded replica structureto create the embosser drum.
 11. The method of claim 10, wherein theusing further comprises: producing a replica of the bonded replicastructure; performing an electroforming process on the at least onesurface of the replica of the bonded replica structure to create ametallic shim, wherein the metallic shim comprises the pattern ofnanometer-scale grooves on at least one surface thereof; and shaping themetallic shim to form the outer surface of the embosser drum.
 12. Themethod of claim 11, wherein the shaping comprises: welding opposing endsurfaces of the metallic shim together to form the embosser drum,wherein the embosser drum comprises only a single seam.
 13. The methodof claim 12, wherein the single seam of the embosser drum extendsgenerally perpendicularly to the nanometer-scale grooves.
 14. The methodof claim 11, further comprising: producing another replica of the bondedreplica structure; performing an electroforming process on at least onesurface of the another replica to create another metallic shim, whereinthe another metallic shim comprises the pattern of nanometer-scalegrooves on at least one surface thereof; and shaping the anothermetallic shim to form an outer surface of another embosser drum.
 15. Themethod of claim 10, wherein the embossing master comprises silicon andthe replicas comprise a polymer.
 16. A method for pre-formatting opticaltape media, the process comprising: obtaining a length of optical tapethat has first and second opposing surfaces; and embossing, using anembosser drum, a pattern of nanometer-scale structures into at least oneof the first and second opposing surfaces, wherein the embosser drum ismanufactured by a process that results in the embosser drum including anouter embossing surface with only a single welded seam therein.
 17. Themethod of claim 16, wherein the embosser drum manufacturing processcomprises the steps of: producing a plurality of replicas of anembossing master that has at least one surface including the pattern ofnanometer-scale structures therein, wherein each of the replicascomprises at least one surface with at least a portion of the pattern ofnanometer-scale structures therein; bonding the plurality of replicastogether to create a bonded replica structure having at least onesurface with the pattern of nanometer-scale structures formed therein,wherein a surface area of the at least one surface of the bonded replicastructure is at least substantially equal to a surface area of an outerembossing surface of the embosser drum to be formed; generating areplica of the bonded replica structure; and using the replica of thebonded replica structure to create the embosser drum.
 18. The method ofclaim 17, wherein the using comprises: forming an embossing plate fromthe replica of the bonded replica structure; and welding opposing endsurfaces of the embossing plate together at the single seam to form theembosser drum.
 19. The method of claim 17, wherein the bonded replicastructure comprises at least one bonding seam between adjacent embossingmaster replicas that extends generally parallel to grooves of thenanostructure pattern.
 20. The method of claim 17, wherein the replicaof the bonded replica structure is devoid of any seams.